In the field of optical communication technologies, an optical signal transmitted from an optical transmitter to an optical fiber (transmission line) is received by an optical receiver. A light receiving element such as a photodiode (PD) or the like is used for the optical receiver. An example of the PD may include a Pin-PD, an avalanche PD (APD) and the like.
Related techniques are disclosed in, for example, Japanese Laid-Open Patent Publication No. 2008-244391.